The present invention relates generally to electronic circuit design using computer simulation techniques. More specifically, but without limitation thereto, the present invention relates to modeling the output waveform of a circuit element driving a distributed resistance-capacitance network.
Methods for modeling the output waveform of a circuit element or cell driving a resistance-capacitance network generally use a Thevenin equivalent model, i.e., a voltage source in series with a resistance, and a load having a single effective capacitance. However, previous methods produced unsatisfactory results using a computer circuit simulation program such as SPICE because the actual waveform delays were found to be more than ten percent larger than those predicted by the simulation program. A method is therefore needed for modeling the output waveform of a cell driving a resistance-capacitance network that compares more closely to the actual output waveform.